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Running one on a 10.25:1 L31 with a aftermarket Vortecs with beehive springs, GM 6492 cam, 1.6 rockers and used all the Proflow 4150 parts on the manifold itself. Thorley tri-ys into a dual 2.5" exhaust. It is all in a 1987 G20 van with a TH400 that has the stock converter and a 3.08 gear. The Mercruiser manifold makes more torque than the Proflow 4150 manifold ever thought about. By comparison the single plane was horrible.
Here is a screen shot launching that van about as hard as I could without a smoke show from the right rear do to the open differential. Brought it up on the converter, walked it off the line, then hammered it. With the gearing it will run ~60 mph in 1st. So roughly a 0-60. I found I can use a screen capture app to record the PF4 Tuner data screen and capture the interior audio at the same time. Kind of slick because you can hear how the engine sounds in realtime with the recorded data which is a step up from a normal datalog.
Was able to get some mandrel bent 2.5" tailpipes over the axle this morning. The L31 350 sounds pretty darn good now too and fairly quiet cruising around with the windows up and the ac cranked up.
The duty cycle is only hitting 60% - ish. Which isnt bad but I would have expected higher. What are the port sizes on that intake? Any pics?
Many of these L31 Vortec head port injected builds run around 0.400 BSFC rather than the rule of thumb 0.450, so lower injector duty cycle is kind of expected to me. The stock 22.1# MPFI upgrade spider from my L31 running 70 psi for 24.6#, supported ~450 hp on my 383, feeding it up to ~5,000 rpm.
Not sure if I have any but will look. The ports match very well to the Etec170 fiber gaskets and the manifold design itself is virtually identical to a square bore vortec performer rpm. It actually looks like a performer rpm cast in cast iron with injector bungs added to the casting.
The Mercruiser manifold makes more torque than the Proflow 4150 manifold ever thought about. By comparison the single plane was horrible.
There is no magic in the "mercruiser" dual plane intake. Where's the before and after dyno graphs?? Why'd you use Vortec's when 113's are vastly superior to 4500? I don't get it.
There is no magic in the "mercruiser" dual plane intake. Where's the before and after dyno graphs?? Why'd you use Vortec's when 113's are vastly superior to 4500? I don't get it.
Because I did not have a good set of 113s laying around. I had a good set of 180cc aftermarket vortecs laying around. I was initially going to run this engine with a L31 injection system on it and even had it bolted on and started re-working a later model P59 Astro van harness before I found the PF4 system.
There absolutely is a big difference in the dual plane manifold, much more torque than the single plane. It is stalling the same converter over 200 rpm higher. The manifold dynamics in regard to the airflow inertia and resonance tuning effects do not magically change when you put injector bungs in the end of the ports. Dual plane makes more torque than a single plane regardless if it is a wet manifold or a dry one.
This was a comparison of a dual plane vs single plane on a LS, both with port injection. The dual plane had dual 1,000 cfm 4150 throttle bodies on it and the single plane had a single 1,000 cfm 4150, not that it mattered at that power level. That is a victor jr vs holley dual quad dual plane manifold. That LS is down 60 ft/lbs at 3,000 rpm with the victor jr compared to the dual plane, so I am not the only claim of this! After the big fat torque gain in the midrange, the dual plane still effectively matched the single plane through 6,500.
The old SBC saw an almost identical change dual plane mercruiser vs the junk 4150 single plane. The dual plane is better everywhere under 5,000 rpm and much more responsive at part-throttle off-idle when accelerating from a stop. Under 3,000 rpm it is a night and day difference in how the engine runs, similar to the difference between the manifolds and the tri-ys. With the dual plane and tri-ys it is a completely different engine. From a stop it absolutely anhilates the right rear tire now if you jump on the throttle too hard.
I have printouts from the runs, but not going to post them because it was an under the table set of runs and the printouts have the shop name in the background of the graphs. I do not want to get my dyno operater friend in trouble for messing with my stuff on a day off while the shop was closed. He has permission to run the dyno tuning his stuff but mine was on a day the shop was closed and he was working up there, the owner probably does not care but I am not willing to take that chance and mess up his ability to work on a day the shop is closed or my avenue for dyno tuning my stuff.
Before I found the PF4 system this is how I had already set up the engine, it has an EFI Connection 24x reluctor behind the timing cover as well. I was going to run CNP to start with, then bounced between it and the L31 distributor.
Awww.... I wanted to see YOUR b4 and after....not some graph of who know's what (looks like it says "Dual Quad" and "Vic Jr"), off the 'net. As you were.
Last edited by Tom 400 CFI; 04-25-2024 at 03:54 PM.
Awww.... I wanted to see YOUR b4 and after....not some graph of who know's what (looks like it says "Dual Quad" and "Vic Jr"), off the 'net. As you were.
My gain was 40 tq at the tire at 2,500 and the dual plane had more torque to 5,000 rpm, then pretty much overlayed the single plane to 5,800 rpm. I also played with a taper spacer on the dual plane. Upside down it was worth about 8 whp compared to the TB bolted right on to the dual plane manifold and no loss of torque anywhere because it did not change the air/fuel ratio unlike spacers under a carb. Dual plane plus spacer had equal power to the single plane from 5,000-5,800 rpm. I do not care about anything over 5,800 rpm because the cam is done well before that.
Graphs. I'm a visual guy so I LOVE graphs! Graphs are fun. Colorful. Interesting. I dig 'em.
It's incredible that OEM's started designing all new, single plane intakes w/the advent of MPFI....when they already had these massive TORK MONSTAH intakes already on their shelves! Crazy.
Graphs. I'm a visual guy so I LOVE graphs! Graphs are fun. Colorful. Interesting. I dig 'em.
It's incredible that OEM's started designing all new, single plane intakes w/the advent of MPFI....when they already had these massive TORK MONSTAH intakes already on their shelves! Crazy.
Its funny that a marine engine that actually requires torque never uses a single plane either. They are always using some kind of dual plane or port fuel injected manifold with longer runners. Even the Indmar manifold I have that has tunnel ram style ports has runners substantially longer than other similar offerings like say a LT1 or Ramjet manifold. The later GM marine manifold is virtually identical to a L31 truck manifold and has runners longer than a crossfire manifold because it promotes torque.
I actually decided to find one of the dual plane MPFI manifolds after a Gearhead-EFI member used one on his S10 build. More than one marine engine owner has made 450+ hp and loads of torque using the dual plane MPFI manifolds as well. Saw a 9:1 marine 383 build with Etec 170s make over 500 ft/lbs with one a couple of years ago.
The S10 guy had a L31 350 with some head work and a Comp 08-502-8 in it. Claimed 389 rwhp and 422 rwtq on a Dynojet with the combination.
Mine through a TH400 in 2nd gear, screaming a clutch fan still put down 348 rwhp @ 5,300 and 387 rwtq @ 3,100 rpm. My GM 6492 cam is a lot smaller as well than that 08-502-8. I need to get it back on the dyno with the tri-ys. Just need to come up with an air cleaner duct for the 454 TBI air cleaner I have to get it plenty of nice cool air. The TBI SBC air cleaner and intake duct are restricting it with 1.6 in/hg of manifold vacuum built at 5,500 rpm.
A buddy of mine is running the first merc dual plane, along with an Edelbrock plenum I also had to run a 92mm LS throttle body on his L31 350 that has a 3.50" stroke crank in place of the stock one that had spun a couple of rod bearings. Has some ported vortecs, a LT4 hotcam and 1.6 rockers. The truck makes gobs of torque across the whole RPM range. He plans to turbo it at some point.
Wait. 113’s are superior to Vortec heads?? When did this happen? Or are you being facetious?
Right?? It's pretty mind blowing, isn't it? He (fast) actually believes this stuff. Or pretends to? Hard to say. Whatever the motive, it's material that's pretty hard to swallow. GM had a head (the 113) that "made more tq than anything ever in history from 0-4500 RPM....so they went and designed a head w/clean sheet port design, that makes LESS tq from 0-4500....for a 0-4500 truck motor. Makes sense!....doesn't it....?
Originally Posted by Fast355
Its funny that a marine engine that actually requires torque never uses a single plane either.
It's not funny, b/c it's not true. Marine engines almost exclusively use a "single plane" intake. They used (recycled) dual planes for a short time. Likely for economic reasons and ease of getting to market w/"EFI".
Originally Posted by Fast355
The later GM marine manifold is virtually identical to a L31 truck manifold and has runners longer than a crossfire manifold because it promotes torque.
Wait....WHUT!?? I thought the CFI was ALL about "low end tork"...it's not good for anything else. Ignore that. The "Marine L31" has what we'd call "mid length runner". Very much like HSR length, and way, WAY shorter than TPI. Shouldn't the marine industry have used a TPI intake on Marine engines??
BTW, nearly all MPFI intakes ARE, single plane intakes. They're packaged/configured/different looking than yer typical old-skool thinking mind goes to when you see "single plane", but they are, single plane intakes.
Last edited by Tom 400 CFI; 04-25-2024 at 10:26 PM.
Wait. 113’s are superior to Vortec heads?? When did this happen? Or are you being facetious?
The 113s ARE superior to Vortecs under 4,500 rpm on the same short block. Hell TBI heads even make more torque than the Vortecs do under ~4,500 rpm.
You would have had to read the thread. I suggested 113s for an 1987 LG4 build because they work very well with their 58cc chambers.
Find the Goodwrench Quest article CHP did around 2000. The L98 aluminum heads had 4% more average torque than the GOOD production Vortecs did and only lost out power wise to them over about 4,500-5,000 rpm. By comparison the Mexican Vortecs are down everywhere.
Right?? It's pretty mind blowing, isn't it? He (fast) actually believes this stuff. Or pretends to? Hard to say. Whatever the motive, it's material that's pretty hard to swallow. GM had a head (the 113) that "made more tq than anything ever in history from 0-4500 RPM....so they went and designed a head w/clean sheet port design, that makes LESS tq from 0-4500....for a 0-4500 truck motor. Makes sense!....doesn't it....?
It's not funny, b/c it's not true. Marine engines almost exclusively use a "single plane" intake. They used (recycled) dual planes for a short time. Likely for economic reasons and ease of getting to market w/"EFI".
Wait....WHUT!?? I thought the CFI was ALL about "low end tork"...it's not good for anything else. Ignore that. The "Marine L31" has what we'd call "mid length runner". Very much like HSR length, and way, WAY shorter than TPI. Shouldn't the marine industry have used a TPI intake on Marine engines??
BTW, nearly all MPFI intakes ARE, single plane intakes. They're packaged/configured/different looking than yer typical old-skool thinking mind goes to when you see "single plane", but they are, single plane intakes.
Well think what you want. IDGAF to be honest. The dual plane far outperforms the single plane in the RPM range I am using it in. Even gave you the dyno chart of a head to head manifold comparison on a Holley dual plane vs victor jr on a LS with both being MPFI and the dual plane blew the single plane away in that test too.
Since you are so smart, if the dual plane approach did not work, why does Holley build and offer one and rate it with a a 1,000 rpm lower starting rpm range than the single plane. The dual plane is rated 1,500-7,000 rpm and the single plane 2,500-7,000. Dyno testing of the Holley single plane showed 24 ft/lbs more torque at lower rpm than the Victor Jr as well in that manifold shootout I pulled that chart from. Maybe you can take Holleys word for it and not mine.
Since you like colorful, squigly lines I remembered another dual plane MPFI manifold that has been tested against a single plane MPFI manifold on a 360 Magnum. Mopar Performance sold the M1 single plane that was allegidly performance oriented to replace the stock long runner barrel intake that had sealing issues in the belly pan. Hughes performance came out with a dual plane similar to the performer rpm air gap after Mopar discontinued the M1s. They have been tested back to back on the same engine and dyno. The M1 was available as both a 2bbl and 4bbl flange. The stock kegger manifold is also on this graph. Hughes dual plane MPFI air gap manifold beat out all of them and it was not even close. At 3,000 rpm on the stock 360 magnum that closely matches the L31 350 in overall setup and power, the dual plane made more than the long runner truck manifold and was nearly 40 hp up at the wheels up on the Mopar Performance single planes. 40 hp @ 3,000 rpm is ~70 ft/lbs of torque more than the single plane. On the 360 magnum with the stock roller cam the dual plane even made more peak HP than the single plane. As I said before the single vs dual plane characteristics do not suddenly change when fuel injectors are hung on the end of the ports. The 4bbl single plane and the dual plane were also still dead even in power production at 5,500. My brothers 98 R/T Dakota had the M1 2bbl on it when he purchased it. We moded a stock kegger from the local junkyard, added a hughes aluminum belly pan and it was a much torquier truck to drive and fuel mileage improved substantially. Out of those intake choices on the 360, I can tell you which one is going to get the truck down the track the quickest and it is not the single planes or the long runner stock manifold. The kegger even modified also suffers from a case of asthma like a stock TPI does at higher rpm.
The Mercruiser dual plane also kicks the PF4 4150 single plane manifold in the pants torque wise and it is not even close. Big gain in useable torque.
Well Fast....at least your providing good, solid, objective data for us. Internet graphs of who-knows-what, Misguided terminology (understanding of single plane (360*) and dual plane (180*) intakes), "some other guy's truck" producing who-knows-what....and best of all, the end results! The "Gobs of tork-o-meter". The "It RIPS-o-meter". The "kicks in the pants-o-meter". And lets not for get...the famous....PEEL-O-METER! How far you were able to do a 1 tire fryer.
The random pictures of random "things" really help drive your points home, too. A random intake, taken of the 'net. Some junky looking van, from somewhere? A video of a tachometer going...up? A pic of "this guy's engine" in a truck....it's all clear now! It's a LOT of rhetoric...that's for sure.
Why didn't the Marine biz put TPI on 113's in boats? Thing would have ripped the outdrives right off the transoms! How come they're not still using dual planes? They're giving up all that pants-kicking TORK!! :bigears:
Last edited by Tom 400 CFI; 04-26-2024 at 09:10 AM.
Well Fast....at least your providing good, solid, objective data for us. Internet graphs of who-knows-what, Misguided terminology (understanding of single plane (360*) and dual plane (180*) intakes), "some other guy's truck" producing who-knows-what....and best of all, the end results! The "Gobs of tork-o-meter". The "It RIPS-o-meter". The "kicks in the pants-o-meter". And lets not for get...the famous....PEEL-O-METER! How far you were able to do a 1 tire fryer.
The random pictures of random "things" really help drive your points home, too. A random intake, taken of the 'net. Some junky looking van, from somewhere? A video of a tachometer going...up? A pic of "this guy's engine" in a truck....it's all clear now! It's a LOT of rhetoric...that's for sure.
Why didn't the Marine biz put TPI on 113's in boats? Thing would have ripped the outdrives right off the transoms! How come they're not still using dual planes? They're giving up all that pants-kicking TORK!! :bigears:
Marine engines did use 113s but only with closed cooling systems.
Get over yourself Tom. I gave you two solid dyno graphs of dual planes making substantially more torque than single planes with port injection on the same engine. They were not random images, they were exact tests on what your refuse to want to believe. Not my loss! Test one yourself sometime or STFU and stop chasing me thread to thread.
Also consider what you are saying is totally wrong. If the runner design and resonance tuning effect did not change the torque production, your mini-ram test should have made equal torque to your Super Ram test and it did not. The dual plane has a resonance effect within the runners, making the overall runner length much longer than a single plane. The reflected wave on the dual plane runners is what helps them boost torque.
All "your" internet-sourced graphs on irrelevant engines are....worthless. This **** is cookoo.
I've shown how to test intakes, in my thread; my dyno sheets, my tests, same engine, back to back. No hyperbole. Back to "story time".
Dual plane vs single plane is fairly the same regardless what engine you test it on. The dual plane MPFI manifold has a very flat torque curve compared to a single plane. Not a ton of data on them for a SBC since the only way to get one is from an old boat. They work, you are just afraid to admit you are wrong.
Here is a dual plane MPFI on a 360 Magnum with a 236/242 on a 110 with nearly 0.600 lift cam. Torque curve of the MPFI dual plane based off the rpm airgap is table top flat. I may have to pickup an air gap and build my own MPFI conversion of one by adding injector bungs seeing the results of the Mopar unit. I am driving a 4,500 lbs box on wheels with a TH400, stock torque converter and 3.08 gears and it is still getting to 60 mph in under 6 seconds with a mild L31 350. It is making torque.
Dual plane vs single plane is fairly the same regardless what engine you test it on. The dual plane MPFI manifold has a very flat torque curve compared to a single plane. Not a ton of data on them for a SBC since the only way to get one is from an old boat. They work, you are just afraid to admit you are wrong.
I'm not "afraid" of anything. I know dual plane intakes work. They've worked, just "fine" for nearly 100 years. What I also know, is that they don't do what you portray them as being able to do. Along w/most of the other outlandish claims that you make....then back up with OTHER PEOPLE's crap. Crap which we and you know nothing about. Questionable case study...at BEST. Totally irrelevant, in most cases. See below....
Originally Posted by Fast355
Here is a dual plane MPFI on a 360 Magnum with a 236/242 on a 110 with nearly 0.600 lift cam. Torque curve of the MPFI dual plane based off the rpm airgap is table top flat. I may have to pickup an air gap and build my own MPFI conversion of one by adding injector bungs seeing the results of the Mopar unit. I am driving a 4,500 lbs box on wheels with a TH400, stock torque converter and 3.08 gears and it is still getting to 60 mph in under 6 seconds with a mild L31 350. It is making torque.
^There we go.^ Random dude, random truck. Just pick some YT vid and throw it up there to make what point? What ever the alternative reality, assertion-of-the-day is, I guess. Whatever. Give'r hell dude. Van the **** out of it.
Last edited by Tom 400 CFI; 04-26-2024 at 03:08 PM.
04-22-2024, 08:34 PM
